slirp/udp.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)udp_usrreq.c        8.4 (Berkeley) 1/21/94
  30  * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
  31  */
  32
  33 /*
  34  * Changes and additions relating to SLiRP
  35  * Copyright (c) 1995 Danny Gasparovski.
  36  *
  37  * Please read the file COPYRIGHT for the
  38  * terms and conditions of the copyright.
  39  */
  40
  41 #include <slirp.h>
  42 #include "ip_icmp.h"
  43
  44 static u_int8_t udp_tos(struct socket *so);
  45
  46 void
  47 udp_init(Slirp *slirp)
  48 {
  49     slirp->udb.so_next = slirp->udb.so_prev = &slirp->udb;
  50     slirp->udp_last_so = &slirp->udb;
  51 }
  52 /* m->m_data  points at ip packet header
  53  * m->m_len   length ip packet
  54  * ip->ip_len length data (IPDU)
  55  */
  56 void
  57 udp_input(register struct mbuf *m, int iphlen)
  58 {
  59         Slirp *slirp = m->slirp;
  60         register struct ip *ip;
  61         register struct udphdr *uh;
  62         int len;
  63         struct ip save_ip;
  64         struct socket *so;
  65
  66         DEBUG_CALL("udp_input");
  67         DEBUG_ARG("m = %lx", (long)m);
  68         DEBUG_ARG("iphlen = %d", iphlen);
  69
  70         /*
  71          * Strip IP options, if any; should skip this,
  72          * make available to user, and use on returned packets,
  73          * but we don't yet have a way to check the checksum
  74          * with options still present.
  75          */
  76         if(iphlen > sizeof(struct ip)) {
  77                 ip_stripoptions(m, (struct mbuf *)0);
  78                 iphlen = sizeof(struct ip);
  79         }
  80
  81         /*
  82          * Get IP and UDP header together in first mbuf.
  83          */
  84         ip = mtod(m, struct ip *);
  85         uh = (struct udphdr *)((caddr_t)ip + iphlen);
  86
  87         /*
  88          * Make mbuf data length reflect UDP length.
  89          * If not enough data to reflect UDP length, drop.
  90          */
  91         len = ntohs((u_int16_t)uh->uh_ulen);
  92
  93         if (ip->ip_len != len) {
  94                 if (len > ip->ip_len) {
  95                         goto bad;
  96                 }
  97                 m_adj(m, len - ip->ip_len);
  98                 ip->ip_len = len;
  99         }
 100
 101         /*
 102          * Save a copy of the IP header in case we want restore it
 103          * for sending an ICMP error message in response.
 104          */
 105         save_ip = *ip;
 106         save_ip.ip_len+= iphlen;         /* tcp_input subtracts this */
 107
 108         /*
 109          * Checksum extended UDP header and data.
 110          */
 111         if (uh->uh_sum) {
 112       memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
 113           ((struct ipovly *)ip)->ih_x1 = 0;
 114           ((struct ipovly *)ip)->ih_len = uh->uh_ulen;
 115           if(cksum(m, len + sizeof(struct ip))) {
 116             goto bad;
 117           }
 118         }
 119
 120         /*
 121          *  handle DHCP/BOOTP
 122          */
 123         if (ntohs(uh->uh_dport) == BOOTP_SERVER) {
 124             bootp_input(m);
 125             goto bad;
 126         }
 127
 128         if (slirp->restricted) {
 129             goto bad;
 130         }
 131
 132         /*
 133          *  handle TFTP
 134          */
 135         if (ntohs(uh->uh_dport) == TFTP_SERVER) {
 136             tftp_input(m);
 137             goto bad;
 138         }
 139
 140         /*
 141          * Locate pcb for datagram.
 142          */
 143         so = slirp->udp_last_so;
 144         if (so->so_lport != uh->uh_sport ||
 145             so->so_laddr.s_addr != ip->ip_src.s_addr) {
 146                 struct socket *tmp;
 147
 148                 for (tmp = slirp->udb.so_next; tmp != &slirp->udb;
 149                      tmp = tmp->so_next) {
 150                         if (tmp->so_lport == uh->uh_sport &&
 151                             tmp->so_laddr.s_addr == ip->ip_src.s_addr) {
 152                                 so = tmp;
 153                                 break;
 154                         }
 155                 }
 156                 if (tmp == &slirp->udb) {
 157                   so = NULL;
 158                 } else {
 159                   slirp->udp_last_so = so;
 160                 }
 161         }
 162
 163         if (so == NULL) {
 164           /*
 165            * If there's no socket for this packet,
 166            * create one
 167            */
 168           so = socreate(slirp);
 169           if (!so) {
 170               goto bad;
 171           }
 172           if(udp_attach(so) == -1) {
 173             DEBUG_MISC((dfd," udp_attach errno = %d-%s\n",
 174                         errno,strerror(errno)));
 175             sofree(so);
 176             goto bad;
 177           }
 178
 179           /*
 180            * Setup fields
 181            */
 182           so->so_laddr = ip->ip_src;
 183           so->so_lport = uh->uh_sport;
 184
 185           if ((so->so_iptos = udp_tos(so)) == 0)
 186             so->so_iptos = ip->ip_tos;
 187
 188           /*
 189            * XXXXX Here, check if it's in udpexec_list,
 190            * and if it is, do the fork_exec() etc.
 191            */
 192         }
 193
 194         so->so_faddr = ip->ip_dst; /* XXX */
 195         so->so_fport = uh->uh_dport; /* XXX */
 196
 197         iphlen += sizeof(struct udphdr);
 198         m->m_len -= iphlen;
 199         m->m_data += iphlen;
 200
 201         /*
 202          * Now we sendto() the packet.
 203          */
 204         if(sosendto(so,m) == -1) {
 205           m->m_len += iphlen;
 206           m->m_data -= iphlen;
 207           *ip=save_ip;
 208           DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno)));
 209           icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
 210         }
 211
 212         m_free(so->so_m);   /* used for ICMP if error on sorecvfrom */
 213
 214         /* restore the orig mbuf packet */
 215         m->m_len += iphlen;
 216         m->m_data -= iphlen;
 217         *ip=save_ip;
 218         so->so_m=m;         /* ICMP backup */
 219
 220         return;
 221 bad:
 222         m_freem(m);
 223         return;
 224 }
 225
 226 int udp_output2(struct socket *so, struct mbuf *m,
 227                 struct sockaddr_in *saddr, struct sockaddr_in *daddr,
 228                 int iptos)
 229 {
 230         register struct udpiphdr *ui;
 231         int error = 0;
 232
 233         DEBUG_CALL("udp_output");
 234         DEBUG_ARG("so = %lx", (long)so);
 235         DEBUG_ARG("m = %lx", (long)m);
 236         DEBUG_ARG("saddr = %lx", (long)saddr->sin_addr.s_addr);
 237         DEBUG_ARG("daddr = %lx", (long)daddr->sin_addr.s_addr);
 238
 239         /*
 240          * Adjust for header
 241          */
 242         m->m_data -= sizeof(struct udpiphdr);
 243         m->m_len += sizeof(struct udpiphdr);
 244
 245         /*
 246          * Fill in mbuf with extended UDP header
 247          * and addresses and length put into network format.
 248          */
 249         ui = mtod(m, struct udpiphdr *);
 250     memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
 251         ui->ui_x1 = 0;
 252         ui->ui_pr = IPPROTO_UDP;
 253         ui->ui_len = htons(m->m_len - sizeof(struct ip));
 254         /* XXXXX Check for from-one-location sockets, or from-any-location sockets */
 255         ui->ui_src = saddr->sin_addr;
 256         ui->ui_dst = daddr->sin_addr;
 257         ui->ui_sport = saddr->sin_port;
 258         ui->ui_dport = daddr->sin_port;
 259         ui->ui_ulen = ui->ui_len;
 260
 261         /*
 262          * Stuff checksum and output datagram.
 263          */
 264         ui->ui_sum = 0;
 265         if ((ui->ui_sum = cksum(m, m->m_len)) == 0)
 266                 ui->ui_sum = 0xffff;
 267         ((struct ip *)ui)->ip_len = m->m_len;
 268
 269         ((struct ip *)ui)->ip_ttl = IPDEFTTL;
 270         ((struct ip *)ui)->ip_tos = iptos;
 271
 272         error = ip_output(so, m);
 273
 274         return (error);
 275 }
 276
 277 int udp_output(struct socket *so, struct mbuf *m,
 278                struct sockaddr_in *addr)
 279
 280 {
 281     Slirp *slirp = so->slirp;
 282     struct sockaddr_in saddr, daddr;
 283
 284     saddr = *addr;
 285     if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
 286         slirp->vnetwork_addr.s_addr) {
 287         uint32_t inv_mask = ~slirp->vnetwork_mask.s_addr;
 288
 289         if ((so->so_faddr.s_addr & inv_mask) == inv_mask) {
 290             saddr.sin_addr = slirp->vhost_addr;
 291         } else if (addr->sin_addr.s_addr == loopback_addr.s_addr ||
 292                    so->so_faddr.s_addr != slirp->vhost_addr.s_addr) {
 293             saddr.sin_addr = so->so_faddr;
 294         }
 295     }
 296     daddr.sin_addr = so->so_laddr;
 297     daddr.sin_port = so->so_lport;
 298
 299     return udp_output2(so, m, &saddr, &daddr, so->so_iptos);
 300 }
 301
 302 int
 303 udp_attach(struct socket *so)
 304 {
 305   if((so->s = socket(AF_INET,SOCK_DGRAM,0)) != -1) {
 306     so->so_expire = curtime + SO_EXPIRE;
 307     insque(so, &so->slirp->udb);
 308   }
 309   return(so->s);
 310 }
 311
 312 void
 313 udp_detach(struct socket *so)
 314 {
 315         closesocket(so->s);
 316         sofree(so);
 317 }
 318
 319 static const struct tos_t udptos[] = {
 320         {0, 53, IPTOS_LOWDELAY, 0},                     /* DNS */
 321         {0, 0, 0, 0}
 322 };
 323
 324 static u_int8_t
 325 udp_tos(struct socket *so)
 326 {
 327         int i = 0;
 328
 329         while(udptos[i].tos) {
 330                 if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
 331                     (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
 332                         so->so_emu = udptos[i].emu;
 333                         return udptos[i].tos;
 334                 }
 335                 i++;
 336         }
 337
 338         return 0;
 339 }
 340
 341 struct socket *
 342 udp_listen(Slirp *slirp, u_int32_t haddr, u_int hport, u_int32_t laddr,
 343            u_int lport, int flags)
 344 {
 345         struct sockaddr_in addr;
 346         struct socket *so;
 347         socklen_t addrlen = sizeof(struct sockaddr_in), opt = 1;
 348
 349         so = socreate(slirp);
 350         if (!so) {
 351             return NULL;
 352         }
 353         so->s = socket(AF_INET,SOCK_DGRAM,0);
 354         so->so_expire = curtime + SO_EXPIRE;
 355         insque(so, &slirp->udb);
 356
 357         addr.sin_family = AF_INET;
 358         addr.sin_addr.s_addr = haddr;
 359         addr.sin_port = hport;
 360
 361         if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
 362                 udp_detach(so);
 363                 return NULL;
 364         }
 365         setsockopt(so->s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
 366
 367         getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
 368         so->so_fport = addr.sin_port;
 369         if (addr.sin_addr.s_addr == 0 ||
 370             addr.sin_addr.s_addr == loopback_addr.s_addr) {
 371            so->so_faddr = slirp->vhost_addr;
 372         } else {
 373            so->so_faddr = addr.sin_addr;
 374         }
 375         so->so_lport = lport;
 376         so->so_laddr.s_addr = laddr;
 377         if (flags != SS_FACCEPTONCE)
 378            so->so_expire = 0;
 379
 380         so->so_state &= SS_PERSISTENT_MASK;
 381         so->so_state |= SS_ISFCONNECTED | flags;
 382
 383         return so;
 384 }